It consists of cooked, vinegar-flavored rice rolled together with raw or cooked fish and vegetables in seaweed known as nori.

It is commonly served with soy sauce, a spicy green paste called wasabi, as well as pickled ginger.

Sushi first became popular in 7th-century Japan as a way to preserve fish.

The cleaned fish was pressed between rice and salt and allowed to ferment for a few weeks until it was ready to eat (1).

Around the middle of the 17th century, people started adding vinegar to the rice as a way to reduce the fermentation time and improve taste.

The fermentation process was abandoned relatively recently in the 19th century, when fresh fish started being used instead of the fermented variety. This gave rise to an early version of the ready-to-eat sushi we're now accustomed to (1).

Fish consumption is also linked to a lower risk of developing certain autoimmune diseases, depression and loss of memory and vision in old age (6, 7, 8, 9, 10).

Wasabi

Wasabi paste is often served alongside sushi. It is very spicy, so it is only eaten in small amounts.

It is made from the grated stem of the Eutrema japonicum plant, which is part of the same family as cabbage, horseradish and mustard.

Wasabi is rich in beta-carotenes, glucosinolates and isothiocyanates. Research shows that these compounds may have anti-bacterial, anti-inflammatory and anti-cancer properties (11, 12, 13, 14).

However, due to the wasabi plant's scarcity, many restaurants use an imitation paste made from a combination of horseradish, mustard powder and green dye, which is unlikely to have the same nutritional properties.

Seaweed

Nori is a type of seaweed used to roll sushi.

It contains many nutrients, including calcium, magnesium, phosphorus, iron, sodium, iodine, thiamine as well as vitamins A, C and E (15).

What's more, 44% of nori's dry weight is protein, which is comparable to high-protein plant foods such as soybeans (16, 17).

However, one roll of sushi contains very little seaweed, which makes it unlikely to contribute to much of your daily nutrient needs.

Studies show that nori may also contain compounds that have the ability to fight viruses, inflammation and perhaps even cancer (18).

Some claim that nori also has the ability to clear heavy metals from the human body.

However, research shows that this property is more likely attributed to brown types of seaweed such as those found in wakame salad (19).

Pickled Ginger

Sweet pickled ginger, also known as gari, is often used to cleanse the palate between different pieces of sushi.

Ginger is a good source of potassium, magnesium, copper and manganese (20).

In addition, it may have certain properties that help protect against bacteria, viruses and perhaps even cancer (21, 22).

Sushi is often thought of as a weight loss friendly meal, but it may not be as beneficial as you think.

That's because many types of sushi are made with high-fat sauces and fried tempura batter, which significantly increases the amount of calories you get.

What's more, a single piece of sushi generally contains very little fish or vegetables. This makes it a low-protein, low-fiber meal and therefore not very effective at reducing hunger and appetite (35, 36).

This perhaps also explains why eating a portion of sushi will leave most people still feeling hungry.

To make your next sushi meal more filling, try accompanying it with a miso soup, a side of edamame beans, a portion of sashimi or a wakame salad.

Bottom Line: Sushi often contains high-fat sauces and toppings, but relatively little vegetables or fish. This can easily turn it into a high-calorie meal that's less likely to make you feel full.

Eating sushi made with raw fish may put you at risk of infection with various bacteria and parasites (40, 41, 42, 43).

Some of the species most often found include Salmonella and various Vibrio bacteria as well as the Anisakis and Diphyllobothrium parasites (44, 45, 46, 47).

It's important to note that the US Food and Drug Administration (FDA) does not currently regulate the use of the "sushi grade fish" label. Because of that, this label does not guarantee that the sushi you are eating is safe.

The only current regulation is that certain fish should be frozen to kill any parasites before being served raw.

One recent study examined the raw fish used in 23 Portuguese restaurants and found that 64% of the samples were contaminated with harmful microorganisms (48).

However, proper food processing and handling procedures can reduce the risk of contamination (49, 50).

If you wish to reduce your risk of contamination, aim to eat sushi at reputable restaurants. These are more likely to follow proper food safety practices. Opting for vegetarian rolls or ones made with cooked fish can also be beneficial.

There are some people that may need to avoid sushi made with raw fish. This includes pregnant women, young children, older adults and those with weakened immune systems.

Bottom Line: Improper food processing and handling practices combined with the use of raw fish and seafood increases the risk of contamination with various bacteria and parasites.